Fuel injection systems



Oct. 20, 1964 T. PATERSON ETAL FUEL INJECTION SYSTEMS Filed Feb. 20, 1961 2 Sheets-Sheet 1 147W M L 5 3,153,405 Patented Oct. 20, 1964 3,153,405 FUEL INJECTION SYSTEMS Thomas Paterson and Zdzislav Stanislav Miracki, London,

England, assignors to Simnrs Motor Units Limited,

London, England, a British company Filed Feb. 20, 1961, Ser. No. 90,559 Claims priority, applicato; (IQ/rent Britain, Feb. 23, 1960,

1 Claim. or. 125-139 The invention relates to fuel injection systems, e.g. for diesel engines or like internal-combustion engines.

The invention provides a fuel injection system comprising a fuel injection pump including a control member movable to control the rate of supply of fuel by the pump, an auxiliary pump for providing a fuel pressure which varies with the speed at which it is driven, a pressure sensitive device on which the said fuel pressure acts to position an abutment member which co-operates with the control member so that the maximum rate at which fuel can be supplied by the-injection pump is set in accordance with the speed of the auxiliary pump. Preferably the fuel injection pump and the auxiliary pump are coupled for operation at the same speed.

Preferably the abutment member is shaped so that the said maximum rate remains substantially the same, or decreases, with increase in speed. 7

Preferably the abutment member is shaped to permit, when the pumps are stopped, the control rod to moveto a position in which the said maximum rate is an excess rate for starting an engine which drives the pumps, and

the abutment member is also shaped so that it interengages with the control member to permit that excess rate to continue until the engine has started.

Preferably the auxiliary pump also serves as a feed pump to supply fuel to the injection pump and acts to pump fuel from the injection pump back to the inlet of the auxiliary pump, thereby to stop the engine, in the event of the engine starting in reverse.

A specific construction of apparatus embodying the invention will now be described by way of example and with reference to the accompanying drawings in which:

FIGURE 1 is an end View of the apparatus, partly in section, taken on the line 11 of FIGURE 2,

FIGURE 2 is a side view, partly in section taken on the line 2-2 of FIGURE 1,

FIGURE 3 is a sectional view taken on the line 33 of FIGURE 2, with certain additional structure indicated diagrammatically.

FIGURE 4 is a greatly enlarged detail sectional view taken on the line 4-4 of FIGURE 3.

In this example the apparatus includes a unit 11 which is secured to one end of a fuel injection pump 12 of the kind known commercially as Simms Type SPE-A, or SPE-B.

The injection pump 12 includes a control rod 13 which is longitudinally movable to control the rate at which fuel is supplied by the injection pump. The injection pump is coupled to a diesel engine so that it supplies fuel from its outlet 61 to the cylinders of the engine in turn as the engine rotates and drives the cam shaft 62 of the injection pump. The control rod 13 is in turn controlled by a centrifugal governor 63 such as is disclosed in the US. Patent to Miracki No. 3,103,822, granted September 17, 1963, which moves the control rod 13 to the right (as viewed in FIGURE 2) when the engine speed rises above the governed speed, thereby rotating the plungers of the injection pump to reduce the rate of supply of fuel by it. When the engine speed drops, the control rod 13 is urged to the left (as viewed in FIGURE 2) to increase the rate of supply of fuel by the injectionpump. The control rod 13 is provided with an extension piece 14 which is threaded into the end of the control rod 13 and is secured in position by a lock nut 15. The extension piece 14 has a rounded end 16 which abuts against an abutment member 17 forming part of the unit 11. The member 17 is in the form of a piston reciprocable in a bore 18 and it is urged to the right (as viewed in FIGURE 1) by means of a helical compression spring 19, the movement of the member 17 under the action of the spring 19 being limited by abutment of a stub 21, carried by the member 17, against the screw plug 22 which closes one end of the bore 18. The chamber 23 within the bore 18 is connected by conduits 24, 43 to the output side of a gear pump comfull load conditions decreases slightly with increase in mounted on a shaft 28 which is an integral extension of" the camshaft 62 of the injection pump 12. The gear 26 is mounted on a stub shaft 29 which is rotatably received in a bore 31. The fuel enters the unit through a conduit 32 and passes through a conduit 42 to the inlet side of the gear pump. The conduit 24 communicates, through a conduit 30 having a restricting orifice 39, with an outlet 33 which is in turn connected, through conduits 64, 65 and a filter 66, to the fuel inlet gallery 67 of the injection pump 12.

When the engine is running normally the fuel pressure provided in the chamber 23 by the gear pump is substantially proportional to the speed of the engine. That pressure urges the member 17 to the left (as viewed in FIG- URE 1) against the action of the spring 19 so that the member 17 takes up a position which is determined by the. speed of the engine. The member 17 has a portion 35 of considerably reduced diameter and when the engine is not running the extension 14 of the control rod 13 abuts against the part 35 of the member 17. The control rod 13 is then further to the left than its position shown in FIGURE 2 and consequently the fuel injection pump is permitted to provide an excess rate of supply of fuel such as is required by the engine when it first starts. When the engine has started and begins to run, the governor moves the control rod to the right (as viewed in FIGURE 2) and thus withdraws the extension 14 from within the annular space 36 surrounding the part 35 of the member 17. That member is thus permitted to move to the left (as viewed in FIGURE 1) when the fuel pressure in the chamber 23 increases with increase in engine speed. The extension 14 of the control rod 13 then abuts against the part 37 of the member 17 when the engine is fully loaded. That part 37 is of tapered form as shown at 38, so that the control rod 13 is consequently moved progressively to the right (as shown in FIGURE 2) when the engine speed progressively increases further, assuming of course that the engine continues to run under full load so that the governor maintains the extension 14 of the control rod in contact with the member 17. The characteristics of the fuel injection pump are such that, in the absence of the applcation of the invention to it, the rate of fuel delivery to the engine under full load increases as the engine speed increases. The above described shaping 38 of the member 37 provides a correction of that effect so that the rate of fuel delivery to the engine under engine speed. The rate of fuel delivery to the engine at low speeds under full load conditions can consequently be increased and greater torque can consequently be obtained from the engine at those lower speeds under full load conditions, without providing excessive rate of fuel supply to the engine when its speed increases under full load conditions.

The construction of this example ensures that the excess rate of fuel supply which is necessary for starting the engine cannot be obtained except when the engine is started.

A by-pass valve 34 is provided between the outlet 33 URE 3.

and theinlet 32. The valve 34 opens when the pressure across it exceeds a predetermined value and so prevents the pressure at the outlet 33 from reaching an excessive value.

The fuel is fed to the conduit 32 through a valve 44 which is normally open to permit fuel to flow to the inlet 32 through conduits 45, 46. The conduit 46 communicates with a valve chamber 47 containing a valve member 48 urged by a spring 49 to the position shown in FIG- In the event of the engine starting in reverse, fuel is pumped under pressure back through the inlet 32. This causes the valve 44 to close and the fuel pressure in the conduit 46 then moves the valve member 48 to open a pressure relieving passage 51. In so moving, the valve member 48 engages with an engine stop control 52 which has a mechanical connection 68 with thecontrolrod 13 and serves to stop the engine by acting on the control rod 13 to cut off the supply offuel to the engine.

A hand operated priming pump 53 is incorporated, having check valves 40, 41.

The invention is-not restricted to the details of the foregoing example.

We claim:

In combination with an internal combustion engine, a fuel injection system comprising a fuel injection pump for feeding fuel to the engine; a control member movable to control the rate of delivery of theinjection pump; an

auxiliary pump having an outlet connected to the injec tion pump and driven by the engine to feed fuel to the injection pump when the engine rotates in the desired direction; a conduit connected to the inlet of the auxiliary pump to supply fuelthereto; a non-return valve. in the conduit to prevent reverse flow of fuel therethrough; a relief valve in the conduit between the non-return valve and the inlet of the auxiliary pump including a valvemember movable under excess pressure of fuel in the conduit to allow escape of fuel therefrom; and an operative connection between the valve-member and the controlmember; whereby when the engine starts to rotate in re verse, the auxiliary pump driven. thereby pumps fuel from its outlet to its inlet and in a reverse direction through the conduit so that the non-return valve closes, excess pressure builds up in the conduit, and the valve-member of the relief valve moves as aforesaid to move the control member to stop the delivery of fuel'by the injection pump to the engine.

References Cited in the file of this patent UNITED STATES PATENTS 1,918,075 Woolson July 11, 1933 2,177,120 Schaeren Oct. 24, 1939 2,195,927 Hurst Apr. 2, 1940 2,222,919 Trapp Nov. 26, 1940 2,716,901 Howe Sept. 6, 1955 2,771,066 Bischofi Nov. 20, 1956 2,810,376 Aldinger Oct. 22, 1957 2,828,728 Dressler Apr. 1, 1958 2,836,162 Nystrom et a1. May 27, 1958 2,855,914 Himes Oct. 14, 1958 FOREIGN PATENTS 566,025 Canada Nov. 11, 1958 529,672 Great Britain Nov. 26, 1940 580,761 Great Britain .Sept. 19, 1946 816,449 Great Britain July 15, 1959 532,426 Italy Aug. 23, 1955 

